The subject matter disclosed herein relates to gas turbine engines.
Gas turbine engines are used in a wide variety of applications, such as power generation, aircraft, and various machinery. Gas turbine engines generally combust a fuel with an oxidant (e.g., air) in a combustor section to generate hot combustion products, which then drive one or more turbine stages of a turbine section. The turbine stages, when driven by the hot combustion products, transfer rotational power to a shaft. The rotating shaft, in turn, drives one or more compressor stages of a compressor section to compress a gas (e.g., oxidant) for intake into the combustor section, and can also drive an electrical generator to produce electrical energy.
Combustor sections of gas turbine engines generally include more than one combustor, where each combustor combusts a fuel/oxidant mixture. The fuel/oxidant mixture has a ratio of fuel to oxidant. In gas turbine systems, such a ratio is often represented by an equivalence ratio, or phi (Φ), which is used to represent the ratio of the actual fuel/oxidant ratio relative to the stoichiometric fuel/oxidant ratio. An equivalence ratio of greater than 1.0 results in a fuel-rich combustion of the fuel and oxidant, where fuel is left uncombusted in the combustion products. On the other hand, an equivalence ratio of less than 1.0 results in a fuel-lean combustion of the fuel and oxidant, where oxidant is left unused in the combustion products.
Because of the relatively large number of variables involved in the combustion process, there may be difficulties in controlling the composition of the combustion products. In situations where the exhaust gas is in certain oxidant-sensitive processes, it may be desirable to maintain the oxidant concentration of the combustion products below a certain threshold.